Treatment of mixed and refractory post-tuberculosis tracheobronchial stenosis with L-shaped silicone stents: case series and a literature review

Abstract

The two patients included in the study had mixed and refractory post-tuberculosis tracheobronchial stenosis (PTTS), having experienced unsuccessful interventional therapies such as balloon dilation and V-shaped stent placement before the operation. Following the secure placement of L-shaped silicone stents, examinations with a fiberbronchoscope during the first and third months post-operation revealed a significant reduction in bronchial mucosa inflammation for both patients. Additionally, the opening diameter of the upper and lower branch segments increased, and chest CT scans indicated a noticeable absorption of left pulmonary lesions. Three months post-operation, fiberbronchoscopy confirmed the stable fixation of the stent without any movement. The patients exhibited substantial improvements in pulmonary function, dyspnea index, and blood gas analysis, with no reported adverse complications. After 7 months, a follow-up fiberbronchoscope for one case revealed excellent stent fixation. Simultaneously, the chest CT scan indicated favorable re-expansion. The placement of L-shaped silicone stents proves effective in preventing displacement, alleviating airway stenosis or obstruction, and ensuring the safety and efficacy of PTTS treatment – particularly in cases where V-shaped silicone stent placement has failed. To our knowledge, this is the first study describing the L-shaped silicone stent in two patients with PTTS.

Plain Language Summary

Successful treatment of severe airway narrowing due to tuberculosis using special L-shaped silicone stents

This article tells the story of two patients who suffered from a complex lung condition called post-tuberculosis tracheobronchial stenosis (PTTS). Imagine your airways - the tubes that carry air to your lungs - getting severely scarred and narrowed due to a past bout with tuberculosis. These two patients had tried previous treatments like balloon dilation (where a small balloon is inflated inside the narrowed airway to widen it) and using V-shaped stents (flexible supports placed in the airway to keep it open), but these methods didn’t provide lasting relief. In this innovative approach, doctors used L-shaped silicone stents specifically designed to fit in the affected parts of the patients’ airways. After placing these stents, regular checks showed remarkable improvements. The swelling in the airway lining reduced significantly, and the openings leading to the upper and lower parts of the lungs got wider. Chest X-rays (CT scans) even showed that the patient’s left lung was healing well. Three months later, the stents stayed firmly in place, and neither patient experienced any problems. Breathing became easier, lung function tests improved, and blood tests showed better oxygen levels. Seven months down the line, one patient continued to do extremely well, with the stent securely fixed and the chest scan showing good lung expansion. This groundbreaking study shows that using L-shaped silicone stents can effectively treat PTTS when other methods fail. Not only do they stay in place, preventing blockages, but they also safely and effectively alleviate narrowing of the airways. It’s the first time such L-shaped stents have been used successfully in PTTS patients, offering new hope for those facing similar challenges.

Introduction

In China, tuberculosis is the main cause of benign airway stenosis.^1,2 Around 30% of tuberculosis patients also have concomitant bronchial tuberculosis. Endobronchial tuberculosis (EBTB) manifests as a tuberculous lesion affecting the bronchial mucosa, submucosa, cartilage, and outer layer, often resulting in diminished work capacity for tuberculosis patients. ³ Diagnosis of EBTB is challenging due to lack of specific clinical features. Consequently, patients with EBTB frequently face the risk of missed or misdiagnosis, leading to irreversible bronchial stenosis, atelectasis, obstructive pneumonia, and, in severe instances, respiratory failure or even fatal suffocation. Therefore, the treatment of EBTB has become a challenge for clinical physicians. In recent years, with the widespread adoption of respiratory intervention technology in clinical diagnosis and treatment, patients with EBTB have benefited from timely interventions, significantly improving their prognosis. ⁴ However, the management of patients with mixed refractory endobronchial tuberculosis presents a complex challenge, as various intervention treatments often fail to effectively alleviate airway obstruction. Even the placement of bronchial stents may be compromised, being displaced toward the distal or proximal bronchus due to the patient’s severe coughing. The presence of bronchial stents, acting as foreign bodies, can stimulate the formation of granulation tissue and lead to the re-narrowing of the airway. This, in turn, can result in obstructive pneumonia, causing the illness to recur and persist. ⁵ Lin et al. reported the utilization of V-shaped stents in the treatment of post-tuberculosis tracheobronchial stenosis (PTTS). Their approach successfully addressed the issue of stent displacement and demonstrated effectiveness during a 1.5-year follow-up observation. ⁶ Inspired by their methodology, we adopted a similar approach and inserted V-shaped silicone stents in 10 patients experiencing left bronchial stenosis during the active phase of tuberculosis. After a 6-month follow-up period, the majority of patients exhibited favorable therapeutic outcomes; however, two patients encountered stent displacement. In the case of one patient (Case 1), stent displacement occurred 8 months after the operation, resulting in the formation of granulation tissue and subsequent lung collapse. Additionally, another patient (Case 2) experienced stents becoming deeply embedded in the carina 3 months post-operation, leading to ventilation and secretion drainage disorders. To solve these challenging problems, the decision was made to remove the stents. However, due to carina injury, reinserting V-shaped or Y-shaped silicone stents was not feasible. Therefore, we innovatively transformed the V-shaped silicone stents into L-shaped stent, with previously used silicone stents from past surgeries and manually stitched them together to create L-shaped stents. The newly constructed L-shaped silicone stents were then meticulously positioned, with one branch in the left main bronchus and the other in the trachea. The L-shaped silicone stent has proven to be highly effective, with positive responses noted during follow-up. The details of the cases are reported as follows. This clinical case report adheres to the CARE (Consensus-based Clinical Case Reporting Guideline) guidelines for reporting clinical cases from the EQUATOR Network. ⁷

Cases presentation

Case 1 involved a 37-year-old female admitted to the hospital due to persistent cough and dyspnea spanning over 2 years, with four unsuccessful attempts at respiratory intervention treatment in an external hospital. The patient’s medical history is unremarkable, with no chronic illnesses reported. The family history indicates no hereditary conditions. Psycho-socially, the patient comes from a stable and supportive environment. No specific genetic information related to airway stent complications is available, but routine genetic testing was not conducted. The patient underwent fiberoptic bronchoscopy at the First Affiliated Hospital of Guangzhou Medical University in July 2021, revealing severe luminal narrowing of the left main bronchus, making bronchoscope insertion impossible. Following treatment, including bronchoscopic balloon dilation and high-frequency electric knife procedures, the patient was discharged. Subsequent bronchoscopic interventions were performed in August 2021, September 2021, and December 2021 at the same hospital, involving high-frequency electric knife treatment and balloon dilation. In the fourth fiberoptic bronchoscopy on 2 December 2021, findings showed severe luminal narrowing (approximately 2 mm) of the left main bronchus, preventing the passage of the bronchoscope. During hospitalization of this patient in our department, V-shaped silicone stents were implanted for treatment. Remarkably, after a 6-month post-operative period, the patient exhibited significant improvement in clinical symptoms, lung function, blood gas analysis, and dyspnea index. However, an 8-month follow-up, including a chest CT scan [Figure 1(a) and (d)], revealed left lung atelectasis, and bronchoscopy identified the distal end of the left branch stent obstructed by granulation tissue at the bronchial opening. We used a 1.2 mm guide wire to explore the distal end of left bronchial for safety. Subsequently, the guide wire was advanced by 4cm, and a 12 mm × 50 mm balloon catheter was employed for dilation. Following the expansion of the distal opening of the left main bronchus to 12 mm, a 12 mm rigid bronchoscope was utilized to carefully extract the existing V-shaped silicone stent [Figure 2(a)–(c)]. A new V-shaped silicone stent, measuring 50 mm × 9 mm for the left branch and 14 mm × 25 mm for the right branch, was meticulously crafted for insertion using the remaining silicone stent material from prior surgeries. However, a bronchoscopy conducted three days after the operation revealed that the right branch stent had slipped into the trachea. Despite multiple attempts, it proved challenging to reposition it in the right main bronchus, leading to the eventual removal of the stent. The rigid bronchoscope was inserted to the distal portion of the left main bronchus, whereupon the necessary stent length was determined using a fiberoptic bronchoscope. We separated the right branch of the stent, which was replaced by a 25 mm × 16 mm silicone stent, sutured it to the left branch to form an L-shaped silicone stent (Figure 3). Deployment of the custom-made L-shaped silicone stent into the left main bronchus and extending to the trachea was achieved via a stent delivery system. Following insertion, the stent was properly expanded utilizing a balloon dilator and meticulously adjusted with rigid forceps to ensure its complete deployment and adequate opening within the designated anatomical locations. The L-shaped silicone stent was successfully implanted into the left main bronchus, while the other branch was positioned in the trachea using a rigid bronchoscopy [Figure 2(d)]. To secure the stent in the trachea, a 16 mm × 50 mm balloon dilator was employed. The follow-up examination 1 week post-operation revealed excellent fixation of the stent, and the chest CT scan 1 month post-operation showed satisfactory re-expansion. The bronchoscopy and CT scan were performed separately 1 week, 1 month, 2 months, 3 months, and 7 months after the operation, which showed the left lung re-expansion [Figures1(b)–(F) and Figures 2(e)–(g)], and the stent was well fixed.

Figure 1.

(a) Chest CT scan suggested left lung atelectasis 8 months after V-shaped silicone stent placement; (b) Left lower lung re-expansion 2 months after L-shaped silicone stent placement. (c) Left lower lung re-expansion 7 months after L-shaped silicone stent placement(coronal view). (d) Chest CT scan suggested left lung atelectasis 8 months after V-shaped silicone stent placement(horizontal view); (e) Left lower lung re-expansion 2 months after L-shaped silicone stent placement (horizontal view). (f) Left lower lung re-expansion 7 months after L-shaped silicone stent placement (horizontal view).

Figure 2.

Bronchoscopic view of the airway. (a) V-shaped silicone stent placement 8 months after surgery (b) V-shaped silicone stent leaded to obstruction of the bronchus by granulation tissue at the distal end (c) Balloon dilatation reopened the left lower bronchus (d) L-shaped silicone stent placement for 1 week (e) Well-fixed L-shaped stent 3 months after surgery (F) Presence of minimal granulation tissue observed at the distal end of the L-shaped stent. (G) Well-fixed L-shaped stent 7 months after surgery.

Figure 3.

The process of L-shaped silicone stent. (a) The initial structure of making an L-shaped silicone stent. (b) scissored the left branch of the stent and stitched it with surgical thread. (c) The left branch of the L-shaped stent was completely stitched with surgical thread.

Case 2 is a 19-year-old female patient who was admitted to our department with a chief complaint of recurrent cough and dyspnea for over 3 months. Both a chest CT scan and bronchoscopy revealed left lung atelectasis [Figures 4(a) and (d) and Figure 5(a) and (b)]. A 10 mm × 40 mm metal-coated stent was successfully implanted in the left main bronchus following balloon dilatation using a Boston Scientific 10 mm × 30 mm three-level balloon [see Figure 5(c)]. However, fibrous granulation tissue obstructed the proximal end of the stent, leading to the recurrence of left lung atelectasis [Figure 5(d)]. Necrotic tissue and proliferative granulation tissue were excised using biopsy forceps, and a stent hook was placed to grasp and pull the metal-coated stent outward. The left main bronchus was reopened via balloon dilation before the insertion of a 10 mm × 50 mm NOVATECH^® GSS™ BD silicone stent [Figure 5(e) and (f)]. Six months after the operation, it was observed that the stent had shifted toward the distal end, causing airflow obstruction in the left lung [Figure 5(g)]. With the patient’s consent, the stent was removed via rigid bronchoscopy and replaced with a V-shaped silicone stent [Figure 5(h)]. Unfortunately, the V-shaped silicone stent became dislodged, resulting in bilateral lung atelectasis three months later. Given the severe damage to the carina [Figure 5(i)], an interdisciplinary decision was made to insert an L-shaped silicone stent. Chest CT scans and bronchoscopies were conducted at 1 week, 1 month, 2 months, and 3 months post-operation, revealing that the L-shaped silicone stent was securely fixed without any signs of displacement [Figure 4(b)–(f) and Figure 5(j)–(l)].

Figure 4.

Chest CT scan images of pre-operation and post-operation of L-shaped silicone stent placement. (a) Preoperative left lung atelectasis (coronal view). (b) Left lung re-expansion after comprehensive treatment (coronal view). (c) three months after L-shaped silicone stent placement. (coronal view). (d) Preoperative left lung atelectasis (horizontal view). (e) Left lung re-expansion after comprehensive treatment (horizontal view). (f) Three months after L-shaped silicone stent placement.

Figure 5.

Bronchoscopic view of the airway of case 2. (a) Stenosis of the left main bronchus. (b) Needle-like stenosis at the distal end of the left bronchus. (c) Placement of a metal-coated stent (d) Formation of granulation tissue caused blockage after stent placement for 3 months. (e) Recanalization through high-frequency electric knife thermal ablation. (f) Placement of a BD stent. (g) Displacement of the BD stent affecting ventilation and drainage of the left upper and lower lungs. (h) Placement of V-shaped silicone treatment. (i) The V-shaped stent deeply embedded in the carina (j) Congestion and erosion of the mucosa of the left main bronchus after removal of the V-shaped stent. (k) Placement of L-shaped stent. (l) 1 month after placement of the L-shaped stent.

The patients provided positive feedback on the received treatment, expressing satisfaction with the overall experience. From their perspective, the interventions have led to an improvement in their health, and they currently feel well.

Discussion

Bronchial tuberculosis is a special type of pulmonary tuberculosis that frequently involves the mucous membrane, submucosa, cartilage, and outer membrane of the tracheobronchial tree. In China, it is a primary cause of benign airway stenosis.^1,2 The bronchial stenosis can be caused by active tuberculosis or scar contracture during recovery, or a combination of both factors. While anti-tuberculosis treatment is effective against active PTTS, respiratory intervention therapy is often necessary to alleviate complications such as stenosis, atelectasis, obstructive pneumonia, and ventilation dysfunction caused by blockage. It’s important to note that respiratory intervention therapy may also induce secondary damage to the bronchi, including thermal ablation and balloon expansion. Such interventions, if exceeding the bronchial mucosa’s capacity for modification, can lead to irreversible damage, affecting the mucous membrane, submucosa, and even bronchial cartilage. In this study, two patients with bronchial tuberculosis were categorized as type VIII bronchial tuberculosis based on the novel classification method introduced by Ding et al. ⁵ Additionally, they were identified as having difficult-to-treat bronchial tuberculosis due to their poor response to standardized treatment.

While thermal ablation and balloon dilation prove effective for the majority of patients with PTTS during the scar period, some individuals with limited efficacy may necessitate the placement of metal stents.^8,9 Although metal stent placement can be successful in some cases, it can also cause severe adhesion to the bronchial wall, which can cause difficulties with secretion discharge, leading to recurrent bronchial infections and granulation tissue formation. This situation necessitates repeated respiratory intervention therapy, imposing significant economic burdens and conflicts for patients, their families, and society. Consequently, in 2003, the United States FDA advocated restricting the use of metal stents for the treatment of benign tracheal stenosis.^10,11 In addition to surgical treatment, silicone stent placement has emerged as the optimal method for addressing benign tracheal and bronchial stenosis. However, the high threshold for silicone stent placement demands a well-coordinated, fully equipped, and advanced medical team, presenting a considerable challenge for many Chinese doctors. Moreover, the reported complication rates associated with silicone stents can be as high as 40–51%.^12,13 Even in our two cases where both metal stent and BD stent were utilized, displacement occurred after stent placement. This suggests that the powerful force generated by cough-induced tracheal and bronchial smooth muscle spasms, especially during the active period of bronchial tuberculosis, can lead to stent displacement. Therefore, preventing stent displacement becomes crucial for improving the treatment of PTTS. In this situation, the consideration of a Y-shaped silicone stent may be appropriate. However, the fixed size and shape of Y-shaped silicone stents pose a challenge, particularly in bronchial tuberculosis patients who often exhibit cartilage damage, lung atelectasis, obstructive pneumonia, and twisted and deformed bronchi with abnormal angles to the trachea, making stent placement difficult. On the other hand, the insertion of a Y-shaped stent may lead to the retention of secretions in the left and right bronchi and trachea, significantly increasing the likelihood of airway infection. ¹⁴ Lin et al. reported a case that used a V-shaped stent to treat bronchial tuberculosis and did not observe displacement during a 1.5-year follow-up. ² Encouraged by this successful case, we applied a V-shaped stent in the treatment of 10 patients. Bronchoscopy examinations revealed a substantial reduction in congestion and edema of bronchial mucosa, and widening of the bronchial opening was evident in all patients. Furthermore, lung function, blood gas analysis, respiratory rate index, and CT scans all exhibited notable improvement at 1 week, 1 month, and 3 months after treatment. Nevertheless, in Case 1, left lung atelectasis occurred 8 months after the operation due to granulation tissue. Despite the removal and subsequent reinsertion of a new V-shaped stent, the right branch silicone stent lacked support due to tracheal injury, preventing proper fixation and resulting in its movement into the trachea. Case 2 experienced multiple stent removals and insertions, causing damage to the prominence and leading to stent displacement due to the loss of soft tissue support. In both cases, neither patient was suitable for V or Y-shaped silicone stent treatment again. As an alternative, L-shaped silicone stents have been employed instead of V or Y-shaped silicone stent placement.

The biggest distinction between the V-shaped silicone stent and the L-shaped silicone stent developed in this study lies in the composition of its left branch. In the L-shaped silicone stent, the left branch utilizes the remaining silicone stent material from previous operations instead of BD stents. To reduce the shear force of the left branch stent, the silicone stent of the left branch is cut with scissors before insertion and cut to a suitable length (30–45 mm) and width (8–10 mm). This method makes the stent lose continuity and greatly lowers its shear force, reducing the chance of mucosal tissue formation. Achieving the appropriate length through precise cutting demands a substantial accumulation of experience. Our observations indicate that, at the current stage, leaning toward a slightly longer length is a comparatively preferable solution, as an excessively extended length can always be adjusted to a shorter one. Prince Ntiamoah et al. reported a novel tool for managing complex benign airway disease with patient-specific silicone airway stents and 3D reconstruction measurement techniques in the medical field to optimize stent sizing. ¹⁵ With the continuous development and utilization of airway stents, various materials and designs, along with their clinical application potential, are on the rise. Of particular note are the applications of 3D printing methods and biodegradable materials. It is anticipated that in the future, new avenues will emerge to overcome the current limitations of airway stents. ¹⁶ Simultaneously, the sewn stent inserted into the bronchus is also more prone to deformation than the finished BD stent as the bronchus undergoes scarring and contraction repair. This characteristic contributes to reducing tissue formation. Moreover, the implantation of the silicone stent in the trachea helps prevent the displacement of the left branch stent. Two patients underwent chest CT scans and fiberoptic bronchoscopy examinations 3 months after the operation, confirming that the L-shaped silicone stent serves as an effective rescue method for the treatment of PTTS following the failure of V-shaped silicone stent insertion.

Conclusion

In summary, active bronchial tuberculosis can lead to airway obstruction and obstructive pneumonia, impacting the efficacy of drug and respiratory intervention treatments. Addressing this issue necessitates the alleviation of airway obstruction. The use of L-shaped silicone stents offers an additional effective and safe method for tackling such challenges. However, determining its suitability as a standard method for preventing stent displacement requires further confirmation through additional cases or multicenter studies.

Supplemental Material

sj-docx-1-tar-10.1177_17534666241254901 – Supplemental material for Treatment of mixed and refractory post-tuberculosis tracheobronchial stenosis with L-shaped silicone stents: case series and a literature review

Supplemental material, sj-docx-1-tar-10.1177_17534666241254901 for Treatment of mixed and refractory post-tuberculosis tracheobronchial stenosis with L-shaped silicone stents: case series and a literature review by Changwen Zhang, Wentao Li, Yu Li, Ni Fang, Mingpeng Xu, Lan Ke, Lifang Li and Guangnan Liu in Therapeutic Advances in Respiratory Disease

Supplemental Material

sj-docx-2-tar-10.1177_17534666241254901 – Supplemental material for Treatment of mixed and refractory post-tuberculosis tracheobronchial stenosis with L-shaped silicone stents: case series and a literature review

Supplemental material, sj-docx-2-tar-10.1177_17534666241254901 for Treatment of mixed and refractory post-tuberculosis tracheobronchial stenosis with L-shaped silicone stents: case series and a literature review by Changwen Zhang, Wentao Li, Yu Li, Ni Fang, Mingpeng Xu, Lan Ke, Lifang Li and Guangnan Liu in Therapeutic Advances in Respiratory Disease